Advice on fourth COVID injection for many Australians could be delayed

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The combination produced 1.75 times the level of neutralizing antibodies to Omicron as the existing Moderna vaccine, the company said. These results, while promising, have yet to be examined through peer review.

If Moderna’s booster is approved for use in the US as predicted, the company’s medical director, Dr. Paul Burton that it was ready to quickly deploy the booster to “as many people as possible around the world”.

Pharmaceutical giant Pfizer is also making an updated booster, which it says would be better at warding off Omicron.

Paul Griffin, an infectious disease expert who has been the principal investigator of seven clinical trials of COVID-19 vaccines, said the evidence around the fourth doses for younger people without risk factors for serious disease was still unclear.

“Right now, there’s no convincing evidence for people who don’t have risk factors to get that fourth dose urgently,” he said.

But this could change soon. Griffin said the new Omicron subvariants showed partial immune evasion to existing vaccines, making people more easily reinfected — even if they’d had their third dose or had been recently infected with coronavirus.

Professor Allen Cheng said the Australian vaccine advisory group is closely monitoring the US, where Moderna will soon be submitting new clinical data.Credit:Simon Schluter

This is because genetic mutations in the spike protein of subvariants BA.4 and BA.5 allow them to evade the immune system’s radar and some of the antibodies we’ve made against other variants.

“There are worrying signs that this is leading to an increase in severity and an increase in hospitalizations worldwide,” Griffin said.

In the The number of hospital admissions for the coronavirus in the UK is rising sharply again. Griffin said there are early signs that this trend in severity is already happening in NSW.

“This is about the ongoing evolution of the virus and the increasing challenges it poses.”

Paul Griffin, infectious diseases expert

“A fourth dose of an Omicron-specific booster may be needed in the not-too-distant future,” he said. “It looks increasingly like this may be the case.”

Professor Tony Cunningham, an infectious disease physician at the Westmead Institute for Medical Research, said the crucial question was: what is likely to happen in the coming months with new variants, such as BA.5, and our antibody levels?

“My guess is it will drop enough that we have to give a fourth dose,” Cunningham said.

Asked about waning immunity for people who received their third dose late last year, Cunningham said data from Israel showed stable protection against serious illness for up to five months. His view was that a variant-specific fourth dose may be needed for longer than six months, especially for high-risk groups such as health professionals and the elderly.

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According to a large new study from Israel, a fourth injection of the Pfizer vaccine provides additional short-term protection against Omicron infections and serious illness in older adults. But it subsides after just four weeks.

Griffin said variant-specific boosters are the future of coronavirus vaccines and can be customized, just like seasonal flu shots.

But he cautioned that fatigue and skepticism about booster shots must be overcome with careful and deliberate health messages.

“A lot of people think that the need for boosters indicates that we did things wrong in the beginning,” he said. “But the fact is, the vaccines do work. This is about the ongoing evolution of the virus and the increasing challenges it poses.”

A fourth dose is currently available to anyone over 65, Aboriginal and Torres Strait Islanders over 50 and Australians under 64 who are immunocompromised.

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